Climate change to slash seafood nutrients by 30% in low-income countries

Climate change could reduce nutrition from seafood by 30 percent for low-income countries by the end of this century, new UBC research suggests.

This is a high carbon emission and low mitigation scenario, according to the study released today Nature climate change. This could drop to roughly 10 percent if the world meets the Paris Agreement’s goal of limiting global warming to 1.5 to 2 degrees Celsius—which recent reports have shown we are not on track to achieve.

Low-income countries and the global South, where seafood is central to the diet and has the potential to help combat malnutrition, are the most vulnerable to the effects of climate change. “For many, seafood is an irreplaceable and affordable source of nutrition.”

Dr. William Cheung, first author, is professor and director of the UBC Institute for the Ocean and Fisheries (IOF).

The researchers examined historical fisheries and mariculture, or mariculture, databases with data from UBC’s Oceans Around Us to find out the amounts of key nutrients obtained through fish and seafood farming in the past, and used predictive climate models to project them into the future. . They focus on four nutrients abundant in seafood and important to human health: calcium, iron, protein and omega-3 fatty acids, the latter of which are not readily available in other food sources.

They found that the availability of this nutrient peaked in the 1990s and stagnated in the 2010s, despite increases in fishing for farmed seafood and invertebrates such as shrimp and oysters.

Calcium saw the biggest decline

Looking to the future, the availability of all four nutrients from projected catch will decline, with calcium taking the biggest hit with projected declines of about 15 to 40 percent by 2100 under low and high emission scenarios, respectively. Omega-3 will see a reduction of about five to 25 percent. These declines are largely driven by reductions in the amount of pelagic fish available for catch.

“Small pelagic fish are really rich in calcium so in areas of the world where people are intolerant to milk or where other animal sources like meat and dairy are very expensive, fish are really key to the human diet,” said senior author Dr. Christina Hicks, Professor at Lancaster University. “In many parts of the world, particularly low-income countries throughout the tropics, fish provide nutrients that are lacking in the human diet.”

Although seafood farming will contribute more nutrients in the future than current levels, the researchers estimate that these increases will not be able to compensate for the loss of fisheries. In a high emissions scenario, any gains in nutrient availability from seafood farming before 2050 will be lost by 2100.

“The primary reason for this is climate change, which is also a significant threat to seafood farming, leaving us with increasing nutrient deficiencies,” said co-author Dr. Muhammed Wainlola, postdoctoral fellow in the UBC Department of Zoology and Institut National de la Recherche Scientifique. “Seafood farming alone cannot provide a comprehensive solution to this complex problem.”

Availability of all four nutrients from tropical waters in generally low-income countries such as Indonesia, Solomon Islands, and Sierra Leone is projected to decline steeply under high-emissions scenarios by the end of this century, compared to minimal declines in high-income countries. , non-tropical waters, such as Canada, the United States and the United Kingdom

Globally, researchers estimate that the availability of nutrients from seafood will decrease by about four to seven percent for every degree Celsius of warming. For low-income countries across the tropics, including Nigeria, Sierra Leone and the Solomon Islands, the projected decline was two to three times this global average, at about 10 to 12 percent per unit of warming.

“This study highlights the impact of each degree of warming,” Dr. Cheung. “The more we can reduce warming, the less the risk to marine and human life.”

A fish uses all

Certain types of fish such as anchovies and herring are nutrient dense but are often used for fish meal and fish oil because these nutrients also promote fish growth. Similarly, many countries retain only selected portions of fish for sale. The researchers highlighted potential adaptations to increase the availability of nutrients from seafood, retain more of these nutritious fish for consumption by local people, as well as reduce food waste in fishery production and consumption by using all parts of fish, including fish heads and fins.

“Future development of seafood supply needs to consider not only economic benefits, but nutritional security of vulnerable groups,” said Dr. Cheung. “But there is a limit to how effective these interventions are, so it is important to limit global warming as much as possible.”